1. Field of the Invention
The present invention relates to a wrapping sheet for perishable goods and more particularly to a wrapping sheet which has the capability of maintaining freshness of perishable goods. Furthermore, the present invention relates to a disposable, biodegradable sheet which can be employed in closed containers as an air freshening device.
2. Description of the Relevant Art
A variety of methods have been employed for keeping perishable goods in a preferable condition in terms of their freshness, etc., during transportation or storage. Additionally, a variety of methods have been employed for controlling odor in closed containers; particularly containers which store biologically derived material such as food products, food waste, and biological waste such as would be found in diaper pails.
At its most simple, odor reduction has been attempted by placing open containers of baking soda material containing sodium bicarbonate in closed volumes such as in refrigerators or freezers. Additionally, in an attempt to control odors, baking soda material has been sprinkled into containers such as garbage cans, diaper pails or the like. These odor reduction methods have undesirable side effects. In the case of placing an open container of baking soda employed in a closed volume such as a refrigerator, the material is prone to be spilled during jostling or arrangement of the food products therein. Additionally, the large container of baking soda provides an inefficient odor reduction media due to the small outer surface area of baking soda actually exposed to the odor causing agents.
In the case of diaper pails, garbage cans and the like, a relatively small volume of baking soda is sprinkled loosely in the bottom of the container. Such methods provide no control over the amount of baking soda employed from container to container and also increases the risk of spillage and also uncontrollable generation of dust as the baking soda is introduced. Finally, the previously proposed methods and devices lack any capacity for absorbing liquid material inadvertently generated in the container. The presence of such unwanted liquid material can be quite undesirable and actually neutralize the effectiveness for the baking soda.
In U.S. Pat. No. 3,084,337 to Someya a packaging material for perishable goods is proposed which comprises a polyethylene or paper sheet into which coral sand granules are impregnated. The sheet can be made into a bag for packaging perishable food stuffs. The coral sand employed has a grain size in the range of 100 to 2000 mesh and evidences a large number of pores having a diameter ranging from about 10 to about 50 micrometers to permit access to active sites on each granule. Coral sand is a hard stony substance formed from the mass skeletons of marine organisms and contains calcium carbonate as its main ingredient with calcium phosphate as its secondary ingredient and trace constituents of magnesium, potassium, iron, sodium strontium and the like also being present. The coral sand employed in this invention is actually contained within the packaging material.
Other references discuss the use of complex polymeric materials, adsorbents or desiccants in sheets which can be employed or with food products. These include U.S. Pat. No. 4,645,698 to Matsubara which discloses a dehydrating and water retaining sheet having a water absorbing agent comprised of a polymeric material which forms a hydrous gel. The sheet also includes a water permeable membrane. U.S. Pat. No. 5,064,698 to Courtright discloses a food packaging material which has a plurality of porous polymeric beads contained therein. The beads are impregnated with an anti-oxidant or oxygen scavenger compound such as iron oxide, BHA, BHT or glucose oxidase. U.S. Pat. No. 4,036,360 to Deffeyes discloses a package which comprises a desiccant material which consists essentially of a desiccant and a tough film forming resin having a high moisture vapor transmission rate; i.e. pre-polymerized polyurethane.
However, no references have been found which teach or suggest a fiber substrate sheet having active sodium bicarbonate stably attached at or adjacent to at least one surface. Thus, it would be desirable to provide a sheet which could be employed in closed containers and would contain sodium bicarbonate securely attached thereto. It would also be desirable that the sodium bicarbonate be present in crystalline or semi-crystalline form and be actively available for the absorption and neutralization of unpleasant odors as well as being present as a perishable food product preservative agent. It would also be desirable that the product be disposable and biodegradable upon such disposal. Finally, it would be desirable that such a product be capable of being produced in an efficient and inexpensive manner.